Selection between audio sources in space (e.g., talkers, musical instruments, etc.) is often performed with beamformers. Many conventional beamformers have a linear processing structure. These existing systems have a three-way tradeoff between (1) hardware size/complexity (e.g., number of microphones), (2) performance, and (3) robustness. Robustness is about graceful degradation with increasing error in the spatial configuration of the desired and interfering acoustic sources. It is very difficult to achieve robustness and good performance with a small number of microphones, and is even a challenge to achieve robustness with a large number of microphones. These problems are a direct result of the mathematical structure of the beamformers.